Sure, but you can also sell something without having built it yourself, just as Microsoft Copilot supports OpenAI and Anthropic models.

It doesn't have to be either/or of course - a cloud provider may well support a range of models, some developed in house and some not.

Vertical integration - a cloud provider building everything they sell - isn't necessarily the most logical business model. Sometimes it makes more sense to buy from a supplier, giving up a bit of margin, than build yourself.

I'm just an observer. Microsoft has invested billions in OpenAI and can access their IP as a result. It might even be possible MS hopes that OpenAI fails and doesn't allow them to restructure to continue to acquire outside funding. You can go directly to the announcement of their in-house model offerings and they are clearly using this as a recruiting tool for talent. Whether it makes sense for the cloud providers to build their own models is not for me to say, but they may not have a choice given how quickly OpenAI/Anthropic are burning cash. If those two fail then they're essentially ceding the market to Google.